Hillary Clinton's defiance in staying in the Democratic race after beating Barack Obama in the Pennsylvania primary paid dividends this morning with a $2.5m (£1.25m) cash injection to her campaign.

Although Clinton made only a minor dent in Obama's delegate lead, claiming 66 delegates with a 55% share of the vote, compared to 57 for Obama (45%), she said the result would give "fresh information" to the superdelegates, anticipating some would take her side.

Speaking to ABC's Good Morning America programme, she said: "The broad-based coalition that I put together is exactly what we're going to need to have in the fall."

She rejected widespread criticism that she had run a negative campaign - the New York Times called her win "the low road to victory". "I'm going to keep running a positive campaign," she said.

Her supporters were given a further fillip this morning with the news that $2.5m in donations streamed in after Pennsylvania was called. Roughly 80% of that was from new donors, according to her team.

Indicating an argument the campaign will take to the remaining uncommitted superdelegates, the Clinton campaign this morning declared she received more votes nationwide than Obama.

The claim, which rests on an analysis by website RealClearPolitics.com, is questionable, as it includes vote tallies from the Michigan and Florida contests that the Democratic party doesn't count. Those elections were held in violation of party scheduling rules.

"Estimates vary slightly, but according to RealClearPolitics, Hillary has received 15,095,663 votes to Sen. Obama's 14,973,720, a margin of more than 120,000 votes," Clinton spokesman Phil Singer wrote in an e-mail to news media. That's a margin of roughly a half percentage point.

In a passionate speech in Philadelphia last night, the New York senator said it was a "long road" to the White House, and that she needed funds for her campaign - which is $10m in the red – to compete with the millions Obama had raised.

"Tonight, more than ever, I need your help to continue this journey ... We can only keep winning if we can keep competing with an opponent who outspends us so massively," she said.

Terry McAuliffe, the chairman of the Clinton campaign, grinning from ear to ear at the victory party, said money was flowing in online as a result of the victory.

Clinton rejected calls from inside the party to bring the protracted contest to an end by standing down. "Some counted me out and said to drop out," she said. "But the American people don't quit. And they deserve a president who doesn't quit either."

Obama, anticipating defeat, had left Pennsylvania early to begin campaigning in Indiana, the next primary on May 6. He congratulated Clinton on running "a terrific race". But he claimed he had done better than expected, defying those who had said he would be "blown out of the water", and had closed the 20-point lead she held at the start of the Pennsylvania campaign.

He spent an estimated $8m on ads in Pennsylvania over the last six weeks, two to three times as much as Clinton, in the hope of knocking her out of the race.

The epic battle between Clinton and Obama looks set to continue through to at least Indiana and possibly even on to the last primary on June 3 or the party convention in Denver in August.

Clinton was helped by winning a majority of older voters, women and the working class. Younger voters, who tend to support Obama, made up a smaller proportion than in previous contests.

There was a clear cultural divide, with a majority of churchgoers, gun-owners and those living in rural areas and small towns opting for Clinton.

Obama may have suffered from the controversy over the views of his pastor, Jeremiah Wright, and his apparently derogatory remarks about those living in small towns.

Most supporters at the Clinton party were unwilling to admit the victory was unlikely to save Clinton from defeat in the long run.

Enid Adler, a local lawyer, was unmoved by warnings that a long race could hurt the party. "That's just an excuse," she said. "This idea of throwing in the towel, that's a mans thing. More and more people are realising she is not going to quit."

Indiana is too close to call but Obama is expected to take North Carolina, held the same day. Clinton expects to take West Virginia and Kentucky while Obama hopes to take Oregon and South Dakota. Montana is too close to call.